This invention relates to an emulsion which may be used when mixed with aggregate for stabilizing the aggregate to produce a product which may include a material for paving, patching or sealing roadways. However, the invention may be used for any purpose where the stabilization of aggregate is necessary, such as building blocks and the like.
Over the years attempts have been made to control the formation of dust on gravel or soil roadways. The processes used for dust control resulted in the use of certain tackifiers and other petroleum based materials. These materials tend to agglomerate the dust particles. Small particles of dust and soil would be formed for a short period of time and this resulted in the control of dust. It was found that when the ambient temperature was relatively cold, below 40.degree. F. to 50.degree. F., this material tended to control dust better than when the ambient temperature was relatively warm, above 90.degree. F., such as during the summer months. During the summer months when ambient temperatures were above 90.degree. F. these dust control agents would adhere to automobile or truck tires resulting in the surface of the roadway being severely damaged. Further, the tires of these vehicles would sink into this soft dust control material whether the ambient temperature was cold or hot. This material was merely a temporary means of controlling dust by covering roadways with a tackifier. Several years later asphalt technology was developed and these gravel and soil roadways were paved with asphalt. Asphalt has characteristics such as weight supporting, repairable, freeze resistant, flexible and impermeable to water. However, due to the expense of paving roadways with asphalt, other alternatives other than asphalt, have been investigated. These alternatives would allow less traveled roadways to contain surfaces similar to asphalt at a reduced cost as compared to asphalt. Many unsuccessful attempts have been made to duplicate asphalt's characteristics with more inexpensive materials.
The instant invention has succeeded in not only duplicating many of the characteristics of asphalt but surprisingly exceeding many of these characteristics with a more economical product. The instant invention provides a novel emulsion, a novel process of stabilizing aggregate for use preferably on roadways and a novel material which may preferably be used as a roadway paving material.
The novel emulsion of the instant invention produces a material which comprises a stabilized aggregate which is bound together sufficiently to withstand stress and pressures associated with heavy vehicles traveling on roadways.
The product of the invention preferably is a paving material used for paving the surfaces of roadways. The product is pliable and consequently will not "break-up" under the maximum allowable highway axle weights of vehicles traveling on these roadways paved with the instant material. The surface of the instant materials are waterproof and actually shed water. These surfaces are actually hard enough so that upon rapid acceleration by automobiles, the tires of these automobiles will not disrupt the surface but will actually leave skid marks on the surface. Furthermore, the instant material is resistant to freeze cycles.
The concentrated emulsion of the instant invention has an excellent shelf life of at least 6 months, may be diluted with water up to 1 part concentrated emulsion to 30 parts water, is environmentally safe, is non-flammable and non-corrosive and may be diluted with hard water over a broad pH range.
U.S. Pat. No. 752,486 issued to Leonard Schade Van Westrum Feb. 16, 1904, discloses a method of forming and maintaining roads, etc. This patent further discloses a means for binding road material together to prevent the disintegration of the road material and the production of dust or dirt. More specifically, '486 teaches dissolving an oily substance in water and sprinkling this oily substance on the roadway. The oils disclosed in '486 are soluable in water, see column 2 lines 72-73 and lines 86-87. The instant mixture of pitch and rosin is not soluble in water. Further, '486 does not use materials, such as, crude oil and tar, see, for example, column 1 line 32. The oils as disclosed in `486, as mentioned, are soluble in water and when applied to a roadway would be solublized by rain water. The material would dissolve and be washed away.
U.S. Pat. No. 2,377,639 to Abraham B. Miller, filed Aug. 10, 1943, discloses a soil stabilization material which comprises a mixture of saponified, substantially petroleum-hydrocarbon insoluable pine wood resin. This material is used to treat soil and especially road soils for use as road building materials. '639 further teaches that some road soils have poor load bearing qualities and the invention disclosed in '639 improves this quality. The composition of the invention as taught in `639 does not contain rosin, see, for example, column 2 lines 11-17. '639 teaches that the pine wood comprises the resinous residue remaining after separation of the rosin from the total resinous extract of the wood. Further, for example, see column 2 line 25-31, where it is stated that extraction of this mixture with a petroleum hydrocarbon dissolves and removes the rosin. In the instant invention, rosin is a critical ingredient along with pitch forming the pine tar mixture for use in the instant emulsion.
U.S. Pat. No. 781,079 to Freidirch Wilhelm Alexander Leobell, issued Jan. 31, 1905, discloses a method of forming or treating roadways by moistening and impregnating the roadways with lyes, resinous ingredients and salts contained in the lyes. The materials used in '079 appears to be calcium lignosulfinate, a waste material from the paper industry. This material is water soluable and has been used for years as a dust control agent on roadways. It is effective as a dust control agent until washed away by rainwater. This material could not be used as a permanent aggregate stabilizing material to produce a stable aggregate as in the instant invention.
U.S. Pat. No. 2,238,776 to Werner E. Kleinicke, issued Apr. 15, 1941, teaches a composition and method for controlling coal dust and for use in soil stabilization in connection with the construction of roadways. This material is a colloid which forms a jel with water. The material is a hydroscopic material which will absorb and retain water vapor from the surrounding air. This type of material will literally absorb water and in some instances be dissolved in water. The material as disclosed in '776 is a dust control agent and absorbs moisture from the air in order to remain moist inorder to control dust. The disadvantage of this characteristic is the fact that after heavy rains the roadways become very muddy or the material is merely dissolved and washed away. This material would be a destabilizing agent as to the instant invention. Further, the composition contains a water soluable crystalizable salt which may be calcium chloride and may further contain an oil, for example, pine oil. Pine oil is separated out in the distillation process in the paper industry at a lower distilation temperature than pitch. Pitch is normally the residue obtained from the distillation process in the paper industry. It is generally refered to as tall oil pitch. Tall oil being a by-product of the alkaline pine wood-pulping process comprised of about equal parts of rosin acids and fatty acids. Further, the oil in '776 may be any suitable mineral, vegetable or animal oil including as mentioned, pine oil or it may include common rosin along with many other suggested synthetic or natural resins. Further, it is taught that the resin is desirable but in no sense essential. Further, '776 teaches, page 3 column 1 lines 22-31, that a major part of the water evaporates from the composition but the crystalizable salt attracts moisture from the atmosphere and maintains the surface of, for example coal or soil, moist. Further, the crystalizable salts as mentioned in page 1 column 1 lines 45-50 are corrosive materials.
U.S. Pat. No. 3,645,947 to Donald J. Quigg, et al., issued Feb. 29, 1972, discloses a rubber emulsion comprising a lactone terpolymer, solvent, emulsifying agent and water and optionaly asphalt and other additives such as tackifiers and extender oils. This material is used to stabilize loose soil formations such as highway surfaces, etc.
U.S. Pat. No. 4,465,518 to Hajime Miyoshi, et al, issued Aug. 14, 1984, discloses a composition for improving the strength of a soft soil composition by treating this material with sulfuric acid and a portland cement.
U.S. Pat. No. 3,399,608 to J. R. Benson, issued Sept. 3, 1968, discloses blending an emulsified asphalt with soil material to provide a stabilized soil structure.
U.S. Pat. No. 1,995,598 to F. M. Archibald, issued Mar. 26, 1935, discloses a method of manufacture of a suitable solution for spraying on to dust laden air or deposited dirt in coal mines, grain elevators, or on roadways. The material comprises a water solution of alkali sulphonate derived from mineral oils and a hydroscopic material. The alkali material may be alkaline earth metals, ammonia or equivalent basic non-metallic compounds. The hydroscopic material may be glycerine or calcium chloride. This material would attract water in the final product after application resulting in the surface of the roadway or coal material remaining moist and in some cases after heavy rain this material would be dissolved and washed away. Further, plasticing materials may be used such as glue, glucose, emulsified asphalt, asphaltic oil, etc. This material may be used with or without the hydroscopic material. The addition of this material, as stated in '598 tends to make the cemented dust controlable. This is a common dust control method i.e., spraying a solution of sodium sulphonate on a dirt road in quantities sufficient to wet the surface and thereby prevent dust from forming for limited periods of time.
Although the above patents rely on different mechanisms to either control dust or form a particle asphalt type soil or aggregate stabilizing composition or generally teach compositions of matter that may be used for the construction of roadways, each suffer from the same common deficiencies, in that, the instant invention utilizes critical amounts of pitch and rosin to form a "pine tar mixture" which is utilized in the instant emulsion. The instant emulsion contains critical maximum emulsified particle sizes of pitch and rosin dispersed therein in order to form a final product which is a stable, weight bearing, flexible, water impermeable, freeze resistant aggregate stabilized material.
In view of the state-of-the-art, it can readily be seen that there is a need for an economical aggregate stabilizing material which has characteristics similar to asphalt but which is much more economical to use. The need has been met since the materials and application of the instant invention are much less expensive and the final product is equivalent to the properties of asphalt.